1. Field of the Invention
The present invention relates to a composition used to remove photoresist during the manufacture of semiconductor devices such as integrated circuits (IC), large-scale integrated circuits (LSI) or very large scale integrated circuits (VLSI), and more particularly, to a photoresist remover composition capable of easily removing, at a low temperature and in a short time, a photoresist layer which is cross-linked during hard baking, dry etching, ashing and/or ion-implantation for photolithography, which are critical processes in producing integrated circuits having a fine pattern, and the photoresist layer cross-linked by metallic contaminants which are shed from a metal layer underneath the photoresist layer during the processes, and capable of minimizing corrosion of a lower metal pattern during removal of the photoresist.
2. Description of the Related Art
In general, during the manufacturing process of semiconductor devices, a photoresist pattern is formed on a conductive layer on a semiconductor device, and then a part of the conductive layer, which is not covered with the pattern, is etched using the pattern as a mask, to form a conductive layer pattern. The photoresist pattern used as the mask should be removed from the conductive layer using a photoresist remover during a cleaning process performed after the formation of the conductive layer pattern. However, recently, semiconductor manufacturing processes have adopted a dry etching process to form a conductive layer pattern, thus removing photoresist during the cleaning process becomes difficult.
The dry etching process, opposed to a wet etching process using acidic chemical solution, is performed through a gas-solid reaction between a plasma etching gas and a material layer such as a conductive layer. The dry etching process can be easily controlled and produces a sharp pattern and thus it is currently leading trend of etching processes. However, during the etching process of the conductive layer, ions and radicals of the plasma etching gas react with the photoresist layer at the surface, so that the photoresist layer is rapidly cured. Accordingly, removing the photoresist becomes difficult.
There are many types of dry etching processes. Reactive ion etching (RIE) is one of these dry etching processes. However, in the case of using the RIE process, it is difficult to reliably remove the photoresist.
Another process which makes the removal of the photoresist difficult is the ion-implantation process. The ion-implantation process is for diffusing phosphorous, arsenic or boron ions into a specific region of a silicon wafer to produce conductivity. The ions are implanted into only a part of the silicon wafer, which is not covered with a photoresist pattern, and simultaneously the photoresist pattern used as a mask for the ion implantation is cross-linked due to a chemical cross-linking reaction with accelerated ion beams at the surface thereof. Thus, it is difficult to remove the photoresist layer after it has undergone ion implantation, by using various solvents in a cleaning process.
Thus, after the photoresist layer has undergone the dry etching or ion-implantation process it cannot be removed using a conventional photoresist remover such as phenol. Also, the cleaning process using phenol is unstable because it requires a soaking process at a high temperature of 100.degree. C. or more for a long time, thereby increasing the failure ratio of semiconductor devices. Due to such a fact, phenolic photoresist removers have been scarcely used in production lines.
Meanwhile, a photoresist remover composition consisting of alkanol amine and diethylene glycol monoalkyl ether has been suggested recently and widely used due to its effective performance in addition to its mild odor and low toxicity. However, the photoresist remover composition cannot remove satisfactorily a photoresist layer exposed to a plasma etching gas or ion beams during the dry etching process or ion-implantation process. Thus, the need for a new photoresist remover capable of removing a photoresist layer cross-linked by dry etching and ion-implantation has increased.
In particular, in the manufacturing process of a VLSI circuit, it is very difficult to remove a photoresist layer which has undergone ion-implantation with a high dose in order to form a source/drain region. During the ion-implantation process, the surface of the photoresist layer is cured by the heat generated from the reaction due to a high dose and high energy of ion beams.
Also, in the ashing process of a semiconductor wafer, photoresist residue may be produced due to a popping phenomenon of the photoresist. The wafer is heated to a high temperature of 200.degree. C. or higher to evaporate the solvent remaining in the photoresist. However, the surface of the photoresist layer is cross-linked after the ion-implantation with a high dose, so that it is difficult to discharge the solvent remaining in the photoresist. As the ashing is performed, the internal pressure of the photoresist layer increases and the surface of the photoresist layer pops due to the solvent existing therein, which is called popping phenomenon. As a result, the cured layer formed at the photoresist surface scatters and it is difficult to remove the resultant residue from the cured layer.
Also, in the case where the surface of the photoresist layer is cured by heat, dopants, i.e. impurities, in the cured layer are substituted for molecules in the molecular structure of photoresist, and cause cross-linking reactions, so that the substituted portion is oxidized by O.sub.2 plasma. The oxidized photoresist changes to residues and particles and acts as a contaminant, thereby lowering yield in VLSI chip production.
In order to effectively remove the cured photoresist layer described above, various dry and wet cleaning processes have been suggested; a two-stage ashing process as one of those processes has been disclosed by Fujimura in a pre-announcement for the Japanese Applied Physics Association in spring (1P-13, page 574, 1989). According to the two-stage ashing process, first ashing is performed by a general method, and secondary ashing is then performed. However, the dry cleaning process is very complicated and requires very large scale equipment, thereby lowering the efficiency of process.
Meanwhile, a photoresist remover composition obtained by mixing an organic amine compound and various organic solvents has been suggested as a photoresist remover for a wet cleaning process. In particular, a photoresist remover composition containing monoethanol amine (MEA) as an essential organic amine component has been widely used.
For example, two-component photoresist remover composition consisting of an organic amine compound such as MEA or 2-(2-aminoethoxy)ethanol (AEE), and a polar solvent such as N,N-dimethylacetamide (DMAc), N,N-dimethylformamide (DMF), N-methylpyrrolidone (NMP), dimethylsulfoxide (DMSO), carbitol acetate or methoxyacetoxypropane (disclosed in U.S. Pat. No. 4,617,251); a two-component photoresist remover composition consisting of an organic amine compound such as MEA, monopropanol amine or methylamylethanol, and an amide solvent such as N-methylacetamide (MAc), N,N-dimethylacetamide (DMAc), N,N-dimethylformamide (DMF), N,N-diethylacetamide (DEAc), N,N-dipropylacetamide (DPAc), N,N-dimethylpropionamide, N,N-diethylbutylamide, N-N-diethylbutylamide or N-methyl-N-ethylpropionamide (disclosed in U.S. Pat. No. 4,770,713); a two-component photoresist remover composition consisting of an organic amine compound including alkanolamine such as MEA, and a non-protonic polar solvent such as 1,3-dimethyl-2-imidazolidinone (DMI) or 1,3-dimethyl-tetrahydropyrimidinon (disclosed in German Patent Laid-Open Publication No. 3,828,513); a photoresist remover composition consisting of an alkanol amine or a polyalkylene polyamine, sulfolane or sulfone compound, and glycol monoalkylether such as diethyleneglycol monoethylether or diethyleneglycol monobutylether in a predetermined mixing ratio (disclosed in Japanese Patent Laid-Open Publication No. Sho 62-49355); a photoresist remover composition consisting of a soluble amine such as MEA or DEA and 1,3-dimethyl-2-imidazolidinone (disclosed in Japanese Patent Laid-Open Publication No. Sho 63-208043); a positive type photoresist remover composition consisting of amines such as MEA, ethylenediamine, piperidine or benzylamine, a polar solvent such as DMAc, NMP or DMSO, and a surfactant (disclosed in Japanese Patent Laid-Open Publication No. Sho 63-231343); a positive type photoresist remover composition consisting of a nitrogen-containing organic hydroxy compound such as MEA, at least one solvent selected from the group consisting of diethyleneglycol monoethyl ether, diethyleneglycol dialkylether, y-butyrolactone and 1,3-dimethyl-2-imidazolidinone, and DMSO (disclosed in Japanese Patent Laid-Open Publication No. Sho 64-42653); a positive photoresist remover composition consisting of an organic amine compound such as MEA, a non-protonic polar solvent such as diethylene glycolmonoalkyl ether, DMAc, NMP or DMSO, and a phosphoricester surfactant (disclosed in Japanese Patent Laid-Open Publication No. Heisei 4-124668); a photoresist remover composition containg water-soluble organic amine compounds such as DMI, DMSO or MEA (disclosed in Japanese Patent Laid-Open Publication No. Heisei 4-350660); and a photoresist remover composition consisting of MEA, DMSO and catechol (disclosed in Japanese Patent Laid-Open Publication No. Heisei 5-281753). In general, these disclosed photoresist remover compositions are excellent in terms of safety, working efficiency and photoresist removing performance.
However, in recent processes for manufacturing semiconductor devices, the processing conditions have become severe, e.g., a high-temperature process at 110.about.140.degree. C. on various substrates including a silicon wafer, so that the photoresist is baked at a high temperature. However, the above-mentioned photoresist removers do not sufficiently remove the photoresist baked at a high temperature. Thus, a photoresist remover composition containing water and/or a hydroxylamine compound has been suggested as a composition for removing the photoresist baked at a high temperature, for example, a photoresist remover composition consisting of hydroxylamines, alkanolamines and water (disclosed in Japanese Patent Laid-Open Publication No. Heisei 4-289866), a photoresist remover composition consisting of amines, alkanolamines, water and a corrosion inhibitor (disclosed in Japanese Patent Laid-Open Publication No. Heisei 6-266119), a photoresist remover composition consisting of polar solvents such as GBL(Gamma Butyrolactone), DMF, DMAc or NMP, amino alcohols such as 2-methylaminoethanol and water (disclosed in Japanese Patent Laid-Open Publication No. Heisei 7-69618), a photoresist remover composition consisting of amino alcohols such as MEA, water and butyldiglycol (disclosed in Japanese Patent Laid-Open Publication No. 8-123043), a photoresist remover composition consisting of alkanolamines or alkoxyalkylamines, glycolmonoalkylether, sugar alcohols, a quaternary ammonium hydroxide and water (disclosed in Japanese Patent Laid-Open Publication No. Heisei 8-262746), a photoresist remover composition consisting of at least one alkanolamine selected from the group consisting of MEA and AEE, hydroxylamine, diethyleneglycolmonoalkylether, sugars (sorbitol) and water (disclosed in Japanese Patent Laid-Open Publication No. Heisei 9-152721), and a photoresist remover composition consisting of hydroxylamines, water, amines having an acid dissociation constant (pKa) of 7.5.about.13, a water-soluble organic solvent and a corrosion inhibitor (disclosed in Japanese Patent Laid-Open Publication No. Heisei 9-96911).
However, the above photoresist remover compositions are not enough to remove a photoresist layer which is processed by the dry etching, ashing and/or ion-implantation, and the photoresist layer cross-linked by metallic contaminants shed from the metal layer underneath the photoresist layer. Also, the anti-corrosion property of these photoresist remover compositions on the metal pattern underneath the photoresist layer during the photoresist removal process is unsatisfactory.